The article cover on the front page mentions 1 TB maximum on the R810 and then 512 GB on page one. The R910 is the 1TB version, the R810 is "only" 512GB. You can also do a single processor in the R810. Though why you would drop the cash on an R810 and a single proc I don't know.Reply

I'm also curious how good it would be at gaming :) I know in many cases these server setups under-perform high end gaming machines, but I'd settle :) Still, something like this would be nice for my side business.Reply

None of the Nehalem-EX numbers are accurate, because Nehalem-EX kernel optimization isn't in Windows 2008 Enterprise. There are only 3 commercial OSes right now that have Nehalem-EX optimization: Windows Server R2 with SQL Server 2008 R2, RHEL 5.5, SLES 11, and soon to be released CentOS 5.5 based on RHEL 5.5. Windows 2008 R1 has trouble scaling to 64 threads, and SQL Server 2008 R1 absolutely hates Nehalem-EX. You are cutting Nehalem-EX benchmarks short by 20% or so by using Windows 2008 R1.

The problem isn't as severe for Magny cours, because the OS sees 4 or 8 sockets of 6 cores each via the enumerator, thus treats it with the same optimization as an 8 socket 8400 series CPU.

It is hard to imagine 4 channels of DDR3-1066 to be 1/3 slower than even the westmere-eps. Can you remove half of the memory dimms to make sure that it isn't Dell's flex memory technology that's slowing things down intentionally to push sales toward R910?Reply

As far as I know, when you only populate two sockets on the R810, the Dell R810 flex memory technology routes the 16 dimms that used to be connected to the 2 empty sockets over to the 2 center CPUs, there could be significant memory bandwidth penalties induced by that.Reply

"This should add a little bit of latency, but more importantly it means that in a four-CPU configuration, the R810 uses only one memory controller per CPU. The same is true for the M910, the blade server version. The result is that the quad-CPU configuration has only half the bandwidth of a server like the Dell R910 which gives each CPU two memory controllers."

Sorry, should have read a little slower. Damn, Dell cut half the memory channels from the R810!!!! That's a retarded design, no wonder the memory bandwidth is so low!!!!!Reply

You read too fast again :-). Only in Quad CPU config. In dual CPU config, you get 4 memory controllers, which connect each two SMBs. So in a dual Config, you get the same bandwidth as you would in another server.

The R810 targets those that are not after the highest CPU processing power, but want the RAS features and 32 DIMM slots. AFAIK, Reply

"It is hard to imagine 4 channels of DDR3-1066 to be 1/3 slower than even the westmere-eps."

On one side you have a parallel half duplex DDR-3 DIMM. On the other side of the SMB you have a serial full duplex SMI. The buffers might not perform this transition fast enough, and there has to be some overhead. I also am still searching for the clockspeed of the IMC. The SMIs are on a different (I/O) clockdomain than the L3-cache.

We will test with Intel's / QSSC quad CPU to see whether the flexmem bridge has any influence. But I don't think it will do much. You might add a bit of latency, but essentially the R810 is working like a dual CPU with four IMCs just like another (Dual CPU) Nehalem EX server system would. Reply

Great article! I like the way in witch you describe the memory subsystem - I have readed the Intel datasheets and many news articles about Xeon 7500, but your description is the best so far.

You say "So each CPU has two memory interfaces that connect to two SMBs that can each drive two channels with two DIMMS. Thus, each CPU supports eight registered DDR3 DIMMs ...", but if I do the math it seems: 2 SMIs x 2 SMBs x 2 channels x 2 DIMMs = 16 DDR3 DIMMs, not 8 as written in the second sentence. Later in the article I think you mention 16 at different places, so it seems it is realy 16 and not 8.

What about Itanium 9300 review (including general background on the plans of OEMs/Intel for IA-64 platform)? Comparision of scalability(HT/QPI)/memory/RAS features of Xeon 7500, Itanium 9300 and Opteron 6000 would be welcome. Also I would like to see a performance comparision with appropriate applications for the RISC mainframe market (HPC?) with 4- and 8-socket AMD, Intel Xeon, Intel Itanium, POWER7, newest SPARC.Reply

I agree. Being able to use all the DIMM slots in the R810 with only half the CPU sockets populated is a neat trick, and I do like having up to 16 drive bays in the R910, but overall the latest IBM 3850 is much more flexible than either of those systems. From a 2 socket 4 cores each system with 32GB RAM up to an 8 socket 8 cores each system with 3TB RAM. Barring some big surprises at HPs announcement in a couple of weeks IBM will be the one to beat in Nehalem EX for the foreseeable future.Reply